Canals

His majesty sent (me) in order to dig 5 canals in Upper Egypt and in order to build 3 barges and 4 tow-boats of acacia wood of Wawat, the rulers of the Medja hills Irtjet, Wawat, Yam, Medja were cutting the wood for them.
(I) did it entirely in one year, floated and loaded with very large granite (blocks) for the pyramid 'Merenre [1] -appears-in-splendor' . Indeed, I made a saving for the Palace with all these 5 canals.

From the autobiography of Weni the ElderTranslated by Mark Vygus

The first major shipping canal was constructed under Pepi I (6th Dynasty), when the rocks of the first cataract were pierced. This helped the Egyptian army to extend their hold on Nubia,
from where raids had been conducted against Upper Egypt. The canal was also of economic significance, enabling the transport of blocks of granite and obelisks downriver on sizable ships. The canal had a length of 90 metres, was ten metres wide and nine metres deep, carved through granite.
Senusret III (12th dynasty) ordered the excavation of a 75 metre long canal at the first cataract which had to be repaired eight years later

Year 8 under the majesty of the king of Upper and Lower Egypt, Khekure (Senusret III), living forever.
His Majesty commanded to make the canal anew, the name of this canal being: "Beautiful-are-the-Ways-of-Khekure-[Living]-Forever," when his majesty proceeded up-river to overthrow Kush, the wretched.
Length of this canal, 150 cubits; width, 20; depth, 15

James Henry Breasted Ancient Records of Egypt Part I § 647

This canal and those like it had to be maintained, or they would become impassible in a short time:

Year 3, first month of the third season, day 22, under the king of Upper and Lower Egypt, Okheperkere (Thutmose I), who is given life. His Majesty commanded to dig this canal, after he found it [stopped up] with stones, (so that) no [ship sailed upon it]. He [sail]ed [down-stream] upon it, his heart [glad, having slain his enemies]. The king's son, Thure.

James Henry Breasted Ancient Records of Egypt Part II § 75

And a generation later, Thutmose III (18th dynasty) had to deal with the problem again and recorded it in almost identical words

His Majesty has ordered that this canal be excavated after he had found it obstructed by rocks and no ship could pass here. With a joyful heart he descended the current after killing his enemies. The name of the canal is "Opening of the way in the beauty of Menkheperre. May he live for ever." The fishermen of Elephantine will re-dig this canal every year.

Ramses III defeated the Libyan Meshwesh by the Water of Re [3] which was seemingly in the western delta. It was also named the Western Canal. According to Breasted it was the continuation of the Bahr Yussuf and came to connect Heracleopolis and Alexandria under the Ptolemies.

A satellite picture of the modern Suez canal and its surroundings.
(This picture is an excerpt from a photograph taken from the NASA Space Shuttle Earth Observations Photography Database)

The easternmost of the seven arms of the Nile used to flow into the Red Sea, east through the depression of Wadi Tumilat into the area taken up nowadays by the Bitter Lakes and from there south to the Red Sea. This gave the ancient Egyptians a direct naval link to East Africa, Arabia and possibly even India. The Tumilat canal seems to have become repeatedly obstructed and reconnected.
The existence of a direct link between the Nile and the Red Sea before the first millennium BCE is speculative. The first documents possibly referring to such a link date to the late Old Kingdom. According to this theory the northern part of this waterway was not navigable anymore by the time of Pepi II. Dismantled ships were transported to the Bitter Lakes and reassembled there [4]. The open sea was reached through the natural waterways connecting the Bitter Lakes and the Red Sea. By the Middle Kingdom the southern part of this route had become blocked too, and under Mentuhotep III Punt had to be reached through Wadi Hammamat. The Tumilat canal was possibly restored during the 12th dynasty and was seemingly navigable during the reigns of Hatshepsut and Thutmose III who made intensive use of their navy for both economic and military ventures. The evidence for the use of the Tumilat route is circumstantial.

Some rulers fortified the approaches to the canal and thus to Egypt as a whole. The Wall of the Prince, a row of fortifications, stretched from the Bitter Lakes to the
Pelusian Mouth of the Nile since the time of Senusret I (12th Dynasty). Ramses II (20th Dynasty) built Pithom and Per Ramses in the Delta.

Despite its strategic and economic value, the canal fell many times into disrepair and only far-sighted pharaohs of major means and power were capable of re-excavating and maintaining it. During the five hundred years following the 20th Dynasty, the canal disappeared under drifting sands.

In the Late Period another attempt at reconstructing the "Suez" canal was made by Necho (or Nekhau, ca.600 BCE), who must have been aware of the military and economic importance of a navigable link between the Mediterranean and the Red Sea.

The Delta
This map is rather a suggestion than a proper map as the courses of the various arms of the Nile changed quite a bit over the centuries.

This man (Necho) was the first who attempted the channel leading to the Erythraian Sea, which Dareios the Persian afterwards completed: the length of this is a voyage of four days, and in breadth it was so dug that two triremes could go side by side driven by oars; and the water is brought into it from the Nile. The channel is conducted a little above the city of Bubastis by Patumos the Arabian city, and runs into the Erythraian Sea: and it is dug first along those parts of the plain of Egypt which lie towards Arabia, just above which run the mountains which extend opposite Memphis, where are the stone-quarries,--along the base of these mountains the channel is conducted from West to East for a great way; and after that it is directed towards a break in the hills and tends from these mountains towards the noon-day and the South Wind to the Arabian gulf. Now in the place where the journey is least and shortest from the Northern to the Southern Sea (which is also called Erythraian), that is from Mount Casion, which is the boundary between Egypt and Syria, the distance is exactly a thousand furlongs to the Arabian gulf; but the channel is much longer, since it is more winding; and in the reign of Necos there perished while digging it twelve myriads of the Egyptians. Now Necos ceased in the midst of his digging, because the utterance of an Oracle impeded him, which was to the effect that he was working for the Barbarian: and the Egyptians call all men Barbarians who do not agree with them in
speech.

After more than one hundred twenty thousand workers had died (according to Herodotus, who possibly exaggerated their number), it was abandoned and left to be finished by the Persian king Darius I, who did much to encourage trade. The canal, 140 km long and 50 metres wide, was opened with great ceremony in 500 BCE. Monuments [7] were erected along the canal (at Tell el-Maskhutah, at the end of Wadi Tumilat, in the Kabret region and near the end of the canal) proclaiming:

A great god is Ahurumazda who has created these heavens, who has created this earth, who has created the humans, who has created the well-being for man, who has created King Darius, who has given Darius the Great Kingship with beautiful horses and men.
I, Darius, Great King, king of kings, king of the countries of all languages, king of the wide and far-off earth, son of Hystaspes the Achaemenid. Darius King says: I, the Persian, with the Persian (soldiers), have taken Egypt. I gave the order to dig this stream from the river which is in Egypt (Piru is its name) to the River Amer sea which comes out of Persia. This stream was dug as I have ordered, and the vessels journeyed on this stream from Egypt to Persia, as I have ordered.

After a French translation in Vincent Scheil, Inscription de Darius à Suez, BIFAO 30 (1931), p.297

The Greek historian and geographer Strabo (63/64 BCE ? ca. CE 24) summed up the history of the canal in his Geography as follows:

The canal was first cut by Sesostris before the Trojan times, but according to other writers, by the son of Psammitichus, who only began the work, and afterwards died; lastly, Darius the First succeeded to the completion of the undertaking, but he desisted from continuing the work, when it was nearly finished,

Strabo, Geography, Book XVII, § 25

Diodorus Siculus who lived in the first century BCE, described the canal as having been re-excavated and being very active in the time of Ptolemy [6] and it remained a major traffic artery for two centuries more. In the reign of Cleopatra, parts of the canal were blocked by sand and only the Roman emperor Trajan (98-117 CE) cleaned it out again and it was called "Trajan's river". Hadrian (117-138 CE) invested in its rebuilding and upkeep as well.

The Fayum region around Lake Moeris could be reached by boat from the Nile by a river arm to which canals were connected. Ptolemais, about twenty kilometres south-east of the nome's capital, Arsinoe, lay by the southernmost canal and was mentioned as a port by Ptolemy. It lay near the end of the navigable part of this canal and was a centre for shipping the agricultural produce of the region.

During the later part of the First Intermediate Period Memphis and the royal 10th dynasty residence at Herakleopolis were connected by a canal 90 km long.

Less spectacular canals were also excavated. Since earliest times irrigation canals were in use. The major ones among them were certainly navigable for shallow draught boats at least during inundation.
In ancient times the Nile was said to have seven mouths [2]. According to Herodotus two of them
were artificial

The Bolbitine and Bucolic mouths are not natural channels but have been excavated.

During the construction of the Gizeh pyramids, a canal was excavated leading to a depression near the pyramids, which could be used as a port for unloading the granite blocks shipped downriver. The water level in all these canals fluctuated greatly being dependent on the level of the Nile. They therefore did not construct quays but beached the boats on the gentle slope of the basin in order to discharge their cargoes.

[1] Merenre (2279-2270) , son of Pepi I (Meryre)[2] The number of Nile mouths changed over the centuries. At times there were as many as 12 major ones.[3] The herds given to the temples of Thebes were given names, one of them in remembrance of the victory of Ramses over the Meshwesh

[4] This is somewhat speculative, based on an inscription of Pepinakht:

Now the majesty of my lord sent me to the country of the Asiatics (aAm[w]) to bring for him the sole companion, [
commander (?)] of the sailors, the caravan conductor, Enenkhet (ananxt), who was building a ship there for Punt, when the Asiatics belonging to the Sand-dwellers (Hr(j)w-Sa) slew him, together with a troop of the army which was with him.

J. H. Breasted, Ancient Records of Egypt, Part One, §360

Breasted himself thought that it was more likely that the Sand-dwellers had been living there or had infiltrated far south along the coast of the Red Sea and reached the region of Wadi Hammamat, a traditional pathway between the Nile valley and the Red Sea. Given the tenuous control the government exercised over these nomadic populations in the border regions this hypothesis has much merit. [6]

An artificial canal leads from the Pelusian arm to the Arabian Gulf and the Red Sea. The first attempt to construct this was made by Necho, the son of Psamtik; The Persian Darius continued the work up to a certain point, but, finally, did not finish it, as he was told that the piercing of the isthmus would cause an inundation of the whole of Egypt, it being proven to him that the Red Sea was more elevated than Egypt. Later Ptolemy II finished the canal, and ordered a lock constructed with much artifice to be built at the most appropriate place. This he had opened before and closed quickly after every passage, thus never leaving it open longer than was necessary. The canal is called Ptolemy after its builder, and at its exit lies a city called Arsinoe.